With demand for the Internet and data services continuing to rise dramatically, today's telecommunications carriers develop infrastructures for providing enhanced data services that are arranged to deliver enormous volumes of packet-based traffic over public networks. At the same time, the infrastructures traditionally used for carrying voice traffic over the public switched telephone network (“PSTN”) lack the capacity to accommodate this increase in data transmission. As a result, a majority of today's telecommunication carriers are seeking cost-effective solutions for delivering voice and data services over a unified infrastructure that bridges the existing divisions between the circuit-switched public switched telephone networks and packet-based networks.
The evolving, next-generation networks offer reliability of the circuit-switched networks as well as the speed and economy of the packet-switched networks. The new networks are typically built on a softswitch-based architecture of media gateways, call servers, and application servers. This architecture is replacing the existing voice hierarchy of access transport, switches, signaling and enhanced service devices. Using the converged networks, service providers and carriers are bundling new services and applications into competitive solutions that are revolutionizing telecommunications marketplace.
A typical converged voice and data network includes a media gateway controller, a media gateway, and a signaling gateway. A media gateway provides an interface between a public switched telephony network and an Internet Protocol network. The media gateway typically terminates several T1 links, which may carry 24 pulse code modulation signals using time-division multiplexing at an overall rate of 1.544 million bits per second (“Mbps”), and uses an encoder to convert a call into a packet format. The media gateway normally offers a range of encoding and compression algorithms such as those recommended by ITU-T, for example, G.711, G.723, G.726, and G.729 to minimize the bandwidth used on a packet network. Media gateway controllers coordinate the activities of media gateways and signaling gateways to setup and tear down calls. Additionally, the media gateway controllers control the enhanced services platforms and provide data to the billing platform for customer billing.
A typical voice and data network further includes a signaling gateway interface between a signaling system 7 (“SS7”) and a packet network. On a public switched telephone network, the signaling system 7 may include a system that puts information required to set up and manage telephone calls in a separate network rather than within the same network that the telephone call is initiated on. Typically, the signaling information is in the form of a digital packet, and the signaling system 7 uses an out-bound-signaling, such that the signaling (control) information travels on a separate, dedicated channel such as a 56 or 64 kilo bites per second (“Kbps”) channel rather than the same channel that is used for the telephone calls. Using the signaling system 7, telephone calls can be set up more efficiently and with greater security, and special services such as call forwarding and wireless roaming services are easier to add and manage than using different types of standards.
Some of the problems associated with using gateways or other internetworking devices known in the art to interconnect computer networks that operate at different transmission capacities, concern scarcity of Internet Protocol (“IP”) addresses. The Internet Protocol is an addressing protocol designed to facilitate routing of data traffic within a network or between networks. The Internet Protocol is used on many computer networks including the Internet, intranets and other networks. Current versions of Internet Protocol, such as a version-4 (“Ipv4”), are becoming obsolete because of the limited address space. With a 32-bit address-field, it is possible to assign 232 different addresses, which is 4,294,967,296, or greater than 4 billion globally unique addresses.
There are two types of Internet Protocol addresses: global Internet Protocol network addresses and local Internet Protocol addresses. Internal sub-networks use local addressing. Local addressing may be either any addressing that is different from Internet Protocol addressing, or non-unique usage of Internet Protocol addresses. In either case, local addresses on a subnet are not used on the external, global Internet. When a device or node using local addressing desires to communicate with the external network, its local address is translated to a common external Internet Protocol address used for communication with an external network by a network address translation device. That is, network address translation allows one or more global Internet Protocol addresses to be shared among a larger number of local addresses.
Internet Protocol masquerading is known in the art and is a Linux networking function similar to the network address translation function. For example, Internet Protocol masquerading allows a set of transport identifiers, such as a Transmission Control Protocol (“TCP”) port, a User Datagram Protocol (“UDP”) port or an Internet Control Message Protocol (“ICMP”) query identifier, to be multiplexed into transport identifiers of a single common external Internet Protocol address. For packets outbound from a private network using local addresses, a masquerading network entity, such as a masquerading gateway, translates a source local Internet Protocol address, source transport identifier and other fields of the outgoing traffic, such as a Transmission Control Protocol field, a User Datagram Protocol field, or an Internet Control Message Protocol checksum field, to an external global Internet Protocol address and external transport identifiers. Thus, the masquerading network device converts the internal connections so that they appear to originate from the masquerading network device itself. For inbound packets, the masquerading network device arranges so that data coming back to a masquerading connection is relayed back to the proper originating network device.
In network systems where one or more network devices share a common address such as an IP address, external devices may communicate with any of the network devices using the common address. However, since each address is shared, the address translation has to take place for data communications with external network devices. Thus, it is desirable to develop a system and methods for improved data forwarding in network systems that employ shared network address mechanisms.